Fixed pupil limiting systems in the form of an aperture stop, adjustable pupil limiting systems in the form of an iris diaphragm, iris openings mechanically constrainedly controlled with zoom position, and motor-driven iris diaphragms, are known from the existing art. These are always opaque mechanical stops that are shaped for the desired limitation of the pupil diameter and allow light beams to pass freely in the region of the pupil and sharply delimit that region.
Also known from the existing art are electronically controlled shutters in LC displays, for example in televisions and computer monitors. The pixel arrays provided in this context allow the brightness value of each individual pixel to be set. All applications of these components serve, however, to emit an image, the so-called shutter matrix being located in the image plane.
Known mechanical pupil limiting systems comprise a fixed aperture or several blades which make possible a predefined, usually approximately circular shape for the pupil in the context of pupil adjustment. The known mechanical pupil limiting systems have the disadvantage that an almost arbitrary pupil shape or a lateral shift of the pupil is possible with them only in very limited fashion or only with great mechanical complexity. Flexible, automated control of pupil limitation, on the other hand, is attracting an increasing level of interest in microscopy.
The known mechanical pupil limiting systems furthermore have the disadvantage that the time required for mechanical adjustment of the aperture is not negligible. With the known mechanical components in particular, rapid adjustment of the aperture is not achievable, or achievable only with great complexity. The structural requirements associated with this lead to high levels of mechanical stress, wear, and noise emission.